Fiber board manufacture



Patented Feb. 9, 1932 JAMES CARNIE, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE MECHANICAL RUBBER; COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF NEW JERSEY FIBER BOARDeMANUFACTURE No Drawing.

erties of water resistance, grease resistance,

electrical insulation, or several of these, and other properties conferred upona fiber sheet by the methods and materials herein recited.

In the manufacture of fiber sheets for special purposes where the fibers are required to be water resistant, grease-proof, it has been the practice to incorporate various ingredients with the fiber prior to its manufacture into sheets or subsequently thereto as by im pregnation or coating. When rubber is incorporated withfibrous material, as for example by theaddition of rubber dispersions to the fiber pulp, the value of the ingredients usually added to increase water resistance, etc. becomes greatly enhanced, and the propertiesof the sheets thus prepared are frequently entirely different than where the rubber is not used.

The primary object of the present invention is to provide a method for incorporating various ingredients with fibrous stock to produce a stiff waterproof fiber board or sheet. Another object is to provide a method for adding such ingredients, to fiber pulp from their dispersions, suspensions or emulsions. A further object is to increase the retentive power of fibers with respect to finely divided sulphur. A further object is to modify the properties of the rubber-containing fiber sheets. Another object is to prepare a waterproof and/or grease-proof fiber sheet having varying degrees of flexibility. Other objects will be apparent fromthe specification and claims.

The invention broadly comprises forming a dispersion of sulphur as a modifying ingredient for fiber sheets, combining the dispersion with fibrous pulp, depositing the sulphur upon the pulp preferably with a material which will aid in retaining the sulphur Application filed May 20,

1930. Serial N0. 454,191.

on the fibers of the pulp ,and subsequently forming the pulp into sheets orother articles.

The addition of rubber to fiber pulp, particularly the addition of rubber derived from latex, increases the retentive power of the fiber sheet for finely divided solids, such as clays, talc and the like, known to the industry asloading materials where it is desired to add such materials. The increased retention may be as much as 50% higher when rubber is present on the fiber than where rubber is not incorporated. Various other materials may be added similarly to the pulp thereby modifying the properties of the sheet with respect to moisture, grease, adhesion, etc. According to the present invention sulphur is to be added to the pulp in the form of a dispersion to confer special properties upon the paper.

' As one example of the invention, a suspension of sulphur is prepared by grinding approximately four parts of sulphur in a ball mill or colloid mill or other suitable apparatus with an aqueous solution containing approximately one part of sodium resinate. The addition of an emulsifying or peptizing agent such as casein, glue, one of the modified starches, soaps, such as the oleates, stearates, or palmitates of sodium, potassium or ammonium, acts to hasten the dispersion of the sulphur and at the same time tends to stabilize the resulting dispersion.

In applying this material to the manufacture of a waterproof fibrous sheet, pulp is prepared for the format-ion of a sheet on any standard type of paper machine by beating the pulp in an ordinary beater or Hollander engine. After the heating process is for instance about three-quarters finished, an

.alkali such as ammonia or caustic soda is added in the proportion of about 7 of the dry. weight of the pulp in the beater. At this stage of the beating processa protective colloid such as one of the modifying starches known as feculoid, or glue, or casein may be added. After the beating is completed, the beater roll is raised off the bed plate and rubber'latex is added. The alkali and protective colloids are added to the suspension of fiber pulp in order to avoid any possible coagulation of the latex when added to the to cause this trouble is that the water may con tain' suspended finely divided lime compounds. By the-addition of the alkali and the protective colloid to the pulp, any acidity of the pulp suspension is neutralized, and the individual particles of pulp and any suspended calcium compound are coated with the particular colloid. Hence, when the latex is added, all risk of coagulation is obviated.

The heater. roll is then made to serve as a means of agitating the pulp and thoroughly mixing the latex therewith. After the latex has become mixed with the pulp the dispersion of sulphur is then added to the contents --then be agglomerated by the addition of an amount of coagulant such as alum insuficient to cause complete coagulation, meanwhile continuing the agitation. When about two-thirds of the quantitv of coagulant necessary to accomplish complete'coagulation has been added, the latex will have become agglomerated but not coagulated upon the pulp. The addition is then stopped for a short time while the agitation is continued. This serves to distribute the agglomerated rubber uniformly upon the fibers, and the rubber will be found adhering to the fiber. It also serves to distribute uniformly on the fiber the aluminum resinate which is formed by the reaction of the resinous size and the alum, which resinate on depositing drags along with it or occludes with it the sulphur in such a manner so that the sulphur too is desirably deposited upon the fiber. The remainder of the coagulation solution is then added to complete the coagulation and to impart an acid reaction to the contents of the beater. The fiber obtained by this treatment is then formed into a finished sheet by any standard papermaking process. The finished sheet will be found to contain approximately 30-35% of the sulphur added to the beater, and the sheet is substantially Waterproof. The degree of re sistance to water may be varied within wide limits by the use of varying quantities of the sulphur and resinate.

Another illustration of the invention is in the production of fiber sheets having high Leashes insulating properties by the addition of an insulating material to the pulp. esinous products, such as cumar resins, phenol aldehyde condensation products, pitches, such as hard wood pitches, may also be added, if desired. These materials can be dispersed in a carrier liquid, preferably water, and they may be added in exactly the same manner as the sulphur dispersion. Loading materials such as clays, talc, etc. may be added as dry powders or as dispersions.

Instead of using a soluble resinate as a dispersing medium for thesulphur, there may be used waxes, synthetic resins, or other resinous materials, casein, glue, soluble soaps of the higher fatty acids, or the sulphur may be added in finely divided form to the pulp Without the use of any of these agents. In-

stead of using water as a carrier liquid there may be used organic solvents, alkalies, such as caustlc soda, or ammonia soap solution,

in fact any suitable menstrum that will allow the sulphur to be deposited as such on the fibers, but the most desirable form of the invention is where a rosin size or resinate is used to assist in depositing and attaching the sulphur to the fibers.

The treated pulp need not contain rubber, although its waterproofing properties are enhanced by such use. The rubber is also beneficial in that it increases the folding properties of a fiber sheet. Rubber may be present from 050% based on the weight of the finished sheet. The rubber dispersion used may be one artificially prepared or a natural dispersion. The treated pulp may be used in other ways than on paper or sheet making apparatus. It may be molded and dried in various forms, such as washers, gaskets, or articles of a similar character with or without the use of vacuum appliances to remove v air, gas or moisture from the article.

Where sulphur and resinous soap are used the mixture may vary from 550% by weight based on the fiber content. Also the propor- '*tion of sulphur to resin material or soap may vary depending on the result desired by the operator. Increase in sulphur increases the stiffness of the board. Sulphur is a good grease-proofing as well as a waterproofing agent.

When the fiber sheet is hot pressed or hot calendered the rosin or similar maternal and sulphur which are in intimate contact with the fiber tend to melt or fuse and thus coat the fiber in an effective manner to render the sheet waterproof. This also gives a desired stiffness to the board or sheet. Instead of using alum any inorganic or organic acid or acid vsalt which gives an acid reaction on hydrolysis may be used in the precipitating operation.

The board or sheets of this invention may also be used as automobile Panel boards or backing boards, boxes or container boards or the like.

With the detailed description 'ven above,

it will be clear that various modi cations may fiber pulp with a non-rubber dispersion containing an organic acid-coagulable material I and finely divided sulphuruntil uniformly mixed with the fibers, adding an acidic material, uniformly depositing sulphur on the fibers, and forming the treated fibers into a sheet. I

2. A process of manufacturing a waterproof fiber sheet which comprises beating a fiber pulp with a dispersion containing 'a resinous material and finely divided'sulphur until uniformly mixed with the fibers, adding an acidic material, uniformly depositing sulphur and resinous material on the fibers, and forming the treated fibers into a sheet.

3. A process of manufacturing a waterproof article which comprises intimately and uniformly mixing a dispersion of rubber and a dispersion containin an organic acid-coagulable material and finely divided sulphur with a fiber pulp, uniformly depositing rubber and sulphur on the fibers, and forming the treated fibers into an article.

4. A .process of manufacturing a waterproof article which comprises intimately and uniformly mixing a dispersion of rubber and a dispersion containing a resinous material and finely, divided sulphur with a fiber pulp, uniformly depositing rubber, resinous material, and sulphur on the fibers, and forming the treated fibers into an article.

5. A process of manufacturing a waterproof fiber sheet or board which comprises beating a fiber pulp with a dispersion containing a soluble resin material havin sulphur dispersed therein, uniformly and rmly depositing upon the fiber the suspended sulphur together with a heavy metal resinate formed from said soluble resin material by the addition of an acidic coagulant, drying, and forming the treated fibers into a sheet or board.

6. A process of manufacturing a waterproof fiber sheet or board which comprises beating a fiber pulp with a dispersion containing a soluble resin material havin sulphur dispersed therein, uniformly and rmly depositing upon the'fiber the suspended sulhur together with a heavy metal resinate ormed from said soluble resin material by the addition of alum, drying, and forming the treated fibers into a sheet or board.

7. A process of manufacturing a waterproof fiber sheet or board which comprises beating a fiber pulp with a dispersion containing a soluble resin material havin sulphur dispersed therein, uniformly and rmly depositing upon the fiber the suspended sulphur together with a heavy metal resinate by the addition of an acidic coagulant, drying, and finally forming the treated fibers into a stifl waterproof sheet or board bv hot pressing or calendering.

8. A process of manufacturing a waterproof fiber sheet or board which comprises intimately and uniformly mixing a dlspersion of rubber and a dispersion containing a soluble metallic resinate having sulphur dispersed therein, uniformly and firmly depositing upon the fibers the suspended rubber and the suspended sulphur together with a heavy metal resinate by the addition of an acidic coagulant, drying, and forming the treated fibers into a stiff waterproof sheet or board.

9. A process of manufacturing a waterproof fiber sheet or board which comprises uniformly mixing together a fiber pulp, water soluble resinous material and finely divided sulphur, converting said resinous material to a water insoluble state, uniformly depositing the resulting water insoluble resinous material and the sulphur on thefiber's, and forming the treated fibers into a stiff sheet or board by hot pressing or hot calendering.

10. A process of manufacturing a waterproof fiber sheet or board which comprises uniformly mixing together a fiber pulp, rosin size and finely divided sulphur, adding a Water soluble heavy metal salt to the mix whereby the resinous material is made water insoluble, uniformly depositing the resulting water insoluble resinous material and the sulphur on the fibers, and forming the treated fibers into a stiff sheet or board by hot pressing or hot calendering.

11. A process of manufacturing a waterproof fiber sheet or board which comprises uniformly mixing together a fiber pulp, rosin size and finely divided sulphur, adding alum A a}, r Laaaa ea firmly associatedl with material contag' rubber, resinous material, andi sulphur.

14:. A waterproof fibrous sheet mafieriai embodying fiber material intimately an& firmly associated with material containing rubber, insoluable metallic resinaise, anci suiphur.

15. A waterprooffibrous sheet material embodying fiber material intimately and firmly associated with material containing a Water insoluble metallic resinate, andi sulphur.

- Signed at Cleveland, county of Cuyahoga, State of Ohio, this 14th day of May, 1930. 15 JAMES CARNIE. 

